1. Field
The general inventive concept relates to a substrate alignment apparatus, and more particularly, to a substrate alignment apparatus, which may finely remove an alignment error between a substrate and a roll at a relatively high speed.
2. Description of the Related Art
A roll to roll process is a process in which a material, wound on a roll, is processed. Roll to roll processing is applied in various printing industries. For example, newspapers are commonly produced using a roll to roll printing technique. As another example, roll to roll processing is used in the production of wrapping paper. For color wrapping paper, the wrapping paper is printed with the colors using several pattern rolls. Printing alignment accuracy required between the wrapping paper and each of the pattern rolls may not be less than about 0.1 mm.
A roll to roll process may allow a flexible substrate, for example, a wrapping paper or a newspaper, to continuously pass through a gap between rolls, and may be capable of achieving relatively high-speed production. Accordingly, the roll to roll process may be applied as a new generation process technique. However, because the substrate may, at times, be unsupported during a roll to roll fabrication process, the roll to roll process technique may be vulnerable to disturbance. Further, because the flexible substrate may be used, an alignment error may be generated due to a variation of the length of the substrate when the tensile force is not uniform. This alignment error may be relatively large, and thus, the roll to roll process may not be easily applied to a liquid crystal display (LCD), an organic light emitting diode (OLED), an organic thin film transistor (OTFT), a plasma display panel (PDP), and/or a solar cell.